The present invention relates to an improved liquid level measuring device with an armless float which is equipped with a pair of multi-point contact arms secured to the float so as to ensure constant abutment of the contact arms against the surface of a metallic circuit path.
On the metallic circuit path are disposed a plurality of fluid discharge ditches defined in any approximate shape so as to permit a thin liquid film formed on the surface of the metallic circuit path, blocking the contact arms from conductive abutment against the metallic circuit path, to be removed continually as the armless float having multi-point contact arms mounted thereto slidably moves along the pole of the liquid level measuring device.
There are many types of liquid measuring devices available on the market, including an original one with an armless float of the present invention, as shown in FIG. 1. The U.S. Pat. No. 5,259,245 issued Nov. 9, 1993, to the present inventor discloses an original liquid level measuring device with an armless float which has been further improved in this invention, making it operate in a safer, and more certain manner.
In the above cited prior art, there are several disadvantages found in its practical application. That level measuring device uses a single contact arm slidable against the pole thereof on which a metallic circuit path is disposed with a plurality of serial resistors disposed thereon. That contact arm is in abutment with the surface of the a metallic circuit path by way of a single projected point. The single point contact makes the measurement of the liquid level difficult to be as precise as required, since the contact can be fluctuant, i. e., the contact between the contact arm and the metallic circuit path will sometimes be interrupted as the contact arm bumps away from the circuit path in sliding movement.
Furthermore, a single point contact makes the resistance between the contact arm and the metallic circuit path larger than a multi-point contact which is disclosed in the present invention.
Besides, the former patent uses an elongated metallic circuit path having a flat and smooth surface. That flat and smooth surface permits a film or coating of a liquid, such as gasoline, in which the measuring device is emerged, easily to be formed thereon. Such thin film or coating blocks the contact arm from effective abutment against the metallic circuit path in operation.
The proceeding problems can be solved if a plurality of liquid discharge ditches of any approximate shapes are defined on the smooth and flat surface, making liquid particles adhered to the surface be easily expelled from the surface as the contact arm is in sliding abutment thereagainst. Thus, the contact arm and the metallic circuit path are surely kept in conductive abutment with each other all the time.
Moreover, the cited former patent of this inventor puts the metallic circuit path on one side of a pole, which is divided into two portions bridged by the slidable contact arm. Such arrangement will render the size of the level measuring device relatively bulky.